Porous fluid cooled electrical conductors

ABSTRACT

Fluid cooled, high current capacity electrical conductors manufactured by spirally rolling or winding porous metal sheet into a desired shape.

Field of Search'..l74/l5 R, 15C, DIG. 6, 126 R, 174/126 CP, 128; 335/216; 333/99 S UIlltd States- Patent I 1 3,715,452 Long a Feb. 6, 1973 541' POROUS FLUID COOLED [5 6] References cm ELECTRICAL CONDUCTORS p UNITED STATES PATENTS [75] Inventor: Hugh M. Long, Tonawanda, NY.

I 3,6l0,8()9 lO/l97l Eigenbrod ..l74/l5 C 73 U C 3,349,]6l l0/l967 [.atham ..l74/DIG. 6 I l l mgr? ER N g New 2,797,392 6/1957 Clogston ..l74/l2 6 R l 3,37l,l45 2/1968 Camille, Jr ..l74/l5 R [22] Filed: JarigZl, 1972 I Y Prim ary Examiner-Bernard A. Gilheany 2 Appl' 219;, Assistant Examiner-A. T. Grimley R l d Application Data Att0mey-Th0mas I. OBrien et al. [62 Division of Ser. No. 875,326, Nov. 10, 1969, Pat. No. 3,636,620.

. [57] ABSTRACT [52] U.S. CL; "174/15 C, 174/126 R, 174/DIG. 6, l v p 1 335/216 Fluid cooled, high current capacity electrical conduc- [5l'] Int.Cl.... ...'.;.i..'....L... .....H0lb"7/34,HOlb 5/00 tOrs manufactured by spirally rolling or winding porous metal sheet into a desired shape.

8 Claims, 2 Drawing Figures nonous rwiucoousn ELECTRICAL CONDUCTORS d'uctors hav inghigh heat transfer surface area perunit volume of conductor are desirableto'ensure that resistive and conductive heat are removed effectively. Although fluid cooled electrical conductors are not new, the prior art hasnot disclosed a satisfactory fluid cooled conductor having extremely high current capacity which can be simplymanufactured.

An object of this invention'is to provide a fluid cooledelectrical conductor having high current carrying capacity, tured.

Another object .is to provide a method of making. I high curre'ritcapacity, fluid cooled electrical conductors;

' Other objects will be. apparent --from the disclosure, d 'g w s ndi m nded' la ms- SUMMARMQ rH-EiNvBNnoN Disclosed herciniis aporousmetal, fluid cooled, elec-' .trical conductor;comprisingspirally wound electrically, conductiveporous metalsheet, rneansjfor introducing and y rernoving-.,e lectrical current joinedlo I each end of such woundmetal sheet, fluid-impermeable electrically nonconductive means; disposed? on i at least the outer surface; ofsuch wound 1 metalsheet; .and fluid conduit means .dispqscdmati-each. end of saidmetal sheet arranged to introduce coolingfluid at one end and discharge warmed fluid atthe other end of said wound porous metal sheetafte'rjflow therethrough. Such conductors can'have longitudinally varying orconstant cross-sectional areas.

' Also disclosed hereinis a methodfor manufacturing a porous metal, fluid cooled, electrical conductor which comprises: (a) providingelectrically conductive porous metalsheet; (M-spirally winding said metal sheet; (c); joining-an electrically:conductive end con-. nector to each end of the wound, porous metalsheet;

(.d)-attaching..fluid conduitmeans to .each end of said woundqporous metal"sheet; and (e) covering the outer surface of said.;wound porous.metal sheet with an electricallytnonconductive, fluid impermeable material;

DESCRl-PTIQN. OF-THE DRAWINGS FIG.- 1 is aperspective viewofa screentwire conduc: tor in the processof beingwound.

.FlG.j2;is across-sectional perspective view ofa conductor prepared according to'this invention.

DETAILED DESCRIPTION It has been foundthat cryogen-cooled conductors capable:of,conducting.many'thousands of amperes of electricitycan' be ma'de in relatively small size from which conductor can be easilymanufacinvention, may have warm and cold ends each with porous metal sheet such as screen wire which is spirally wo'und into a desired shape. In operatiomcryogenic coolant is passed through the porous conductor to cool same and to maintain a desired temperature profile thereinmThe spirally wound porous metal sheet forms an electrically conductive porous structure having a ratio of void space volume to total volume such that cooling fluid may pass therethrough with low. resistance. A useful void space range based on adequate heat transfer surface, low resistance to coolant flow and structural strength considerations has been determined from experiments and calculations'to be about 50 to percent void. Although the preferred porous metal sheeting is screen wire, expanded metal sheeting, perforated metal sheeting and the like may also .be used for constructing fluid cooled electrical conductors of this invention.

Conductors of this invention may be manufactured with various cross-sectional shapes such as circular, annular, elliptical and substantially flat. Also, two or more such porous metal conductors can be concentrically arranged and cooled together or individually. In addition,

should alongitudinally varying cross-sectional area be desired,the porous metal sheet can be 'cut to aspattern prior to spiral' winding, which pattern-when wound yields the desired cross-sectional area variation with conductor'length.

The spirally'wound porous metal conductor of this CI'OSSfSCCllOHQIsQI'EflS which exceedthe cross sectional areaofthecentralportion of the conductonAlthough this, particular configuration is a separate invention claimed in copending application, Ser. No. 875,l l5 filedNov. l0, i969, now, U.S .Pat. Ser. No. 3,610,809,

in thename of LesterK. Eigenbroad the method ofthe instantinventionmay be used to manufacture a conduetor of such configpration.

Improved,transverse electrical conduction can be obtained by means of bonding contiguous windings together, e.g., by placing solder or otherisuitable electrically conductive bonding material on the metal .sc'reen wire in the area of varying cross-section and bonding such contiguous screen wire windings subsequentto or during spiral winding of the conductor, forexample, as by applying appropriate heat to solder coatedwindings.

Fluid coolingcan best be accomplished .by covering theexposed conductor surface with an electrically non conductive, fluid impermeable material to ensure that terminal connections to the porous metal conductor as,

well as distribute electrical current flowuniformly over the ends of the spirally wound porous metal sheet are a requiredpart of this invention. Additionally, such. end connectors can be arranged to permit passage of cool-,

ing fluid through the wound porous metal portion of the conductor by means of appropriate passage or consolid copper or copper alloy and such end connectors joined to the spirally wound metal screen wire by duit means within or attached to said end connectors.

Bonding of the end connectors to the wound porous metal portion can be accomplished by soldering, metal casting or other metal bonding methods. The end connector's may be cast in contact with the wound porous metal sheet thereby achieving both the fabrication of the end connector and its bonding to the wound porous metal sheet in one step.

FIG. 1 depicts a manufacturing method of this invention. Screen wire sheet 1 has been partially wound around mandrel '2. This screen wire sheet has been cut bodiment of this invention comprising a wound screen wire conductor as shown-in preparation in FIG. 1. The

mandrel has been removed, from screen wire portion 1- and replaced with an electrically nonconductive plug 5. Solder portions3 are also shown in cross-section. This conductor has its exposed surface covered with an electrically nonconductive, gas impermeable covering 6 which is provided to ensure that cooling fluid which entersthe conductor through conduit passage 7 mounted in electrically conductive end connector 8 passes.

through wound screen wire 1 and exits through conduit passage 9 in end connector 10. Polyurethane impregnated crepe paper has been found to be a suitable covering material. Terminal posts 12 and 13 are also mounted in end connectors 8 and respectively. End connectors 8 and 10 are bonded to wound screen wire 1 by means of solder. If a large inner diameterhollow conduc'tor'is desired, as would-result from using a large diameter mandrel, the inner surface of such a spirally wound hollow conductor can be covered with an electrically'nondonductive, fluid impermeable material as is the o'utersurface, in lieu of the mandrel being replaced with a-nonconductive' plug.

' EXAMPLE 1 In an example of the conductors ofthis invention, a

conductor similar'to that shown being wound in FIG. 1

may be prepared from spirally wound 90-10 brass, 30 mesh X 0.0l35 inch diameter wire cut as shown in FIG.

means of solder. Electrically nonconductive gas impermeable covering also shown in FIG. 2 may be of polyurethane impregnated crepe paper. Terminal posts as well as gas conduit means shown in FIG. 2 could also be of solid copper or copper alloy. The electrically nonconductive plug shown in FIG. 2 would preferably be made of polytetrafluoroethylene. Solder portions 3 shown in FIG. 2 may be heated subsequent to winding to achieve bonding'of contiguous screenwire layers which as heretofore stated would improve transverse electrical conductivity in the screen wire portion of the conductor. The size of such a conductor would b determined by its service requirements.

Although preferred embodiments of the invention have been described in detail, it is to be understood that modifications and variations may be effected without departing from the spirit and scope of the invention.

What is claimed is:

l. A porous metal, fluid cooled, electrical conductor comprising spirally wound electrically conductive porous metal sheet; means for introducing and removing electrical current joined to each end of such wound metal sheet; fluid impermeable, electrically nonconductive means disposed on at least the outer surface of said wound metal sheet; and fluid conduit means disposed at each end of said wound metal sheet arranged to introduce cold fluid at one end and discharge warmed fluid at the other end of said warmed porous metal sheet after flow thereth'rough.

2. A conductor as described in claim 1 wherein the to 95 percent void. I

3. A conductor as described in claim 1' wherein the porous metal sheetcomprises metal screen wire.

4. A conductor as described in claim 1 wherein the wound porous metal sheet has a longitudinally varying cross-sectional area.

5. A conductor as described in claim 1 wherein the wound porous metal sheet has a longitudinally constant cross-sectional area.

6. A conductor as described in claim 1 wherein at least part of the. contiguous porous metal sheet windings are metal bounded together.

'7. A conductor as described in claim 6 wherein the bond comprises solder.

8. A conductor as described in claim 1 which conductor is hollow having an inner and outer surface, wherein the fluid impermeable electrically nonconductive means is disposed over said inner and outer surfaces. 

1. A porous metal, fluid cooled, electrical conductor comprising spirally wound electrically conductive porous metal sheet; means for introducing and removing electrical current joined to each end of such wound metal sheet; fluid impermeable, electrically nonconductive means disposed on at least the outer surface of said wound metal sheet; and fluid conduit means disposed at each end of said wound metal sheet arranged to introduce cold fluid at one end and discharge warmed fluid at the other end of said warmed porous metal sheet after flow therethrough.
 2. A conductor as described in claim 1 wherein the wound metal sheet has a void space range of about 50 to 95 percent void.
 3. A conductor as described in claim 1 wherein the porous metal sheet comprises metal screen wire.
 4. A conductor as described in claim 1 wherein the wound porous metal sheet has a longitudinally varying cross-sectional area.
 5. A conductor as described in claim 1 wherein the wound porous metal sheet has a longitudinally constant cross-sectional area.
 6. A conductor as described in claim 1 wherein at least part of the contiguous porous metal sheet windings are metal bounded together.
 7. A conductor as described in claim 6 wherein the bond comprises solder. 